As I am working with multiple repairs and waiting on parts I want to start getting an idea of what could be going on.

This I noticed after running the engine just recently before taking it all apart again. Felt and sounded great idling and revving.

Could it be related to my valve adjustment? Could it be carb related? Electrical or timing? The plugs look a little wet/dark while #'s 2 & 4 look normal. Couldn't say for sure yet but I think I did a fantastic job rebuilding these carbs for the 1st time ever if I can say so myself. But idk. Whatever it is I hope it's just an adjustment.

If your confident the spark is ok then it will be carb issues. Does it stay cool only on idle? Do they warm up when at higher revs? Is it standard air filter or pods etc ... I am no expert but I have learned a few things that were going on in my 650. Rich

Last edited by Riche on Wed Jan 31, 2018 3:20 am, edited 1 time in total.

Riche wrote:If your confident the spark is ok then it will be carb issues. Does it stay cool only on idle? Do they warm up when at higher revs? Is it standard air filter or pods etc ... I am no expert but I have leaned a few things that were going on in my 650. Rich

thanks. I'll get back to you in a bit on this. Gotta take care of head cover leaks, loctite some choke plates screws and then I'll be able to start it up again and do more testing...

Riche wrote:If your confident the spark is ok then it will be carb issues. Does it stay cool only on idle? Do they warm up when at higher revs? Is it standard air filter or pods etc ... I am no expert but I have learned a few things that were going on in my 650. Rich

okay, so I tried again after adjusting valve clearances. No change. I also tried putting 2 & 4 cables in 1 & 3 sockets and 1 & 3 plugs in 2 & 4 sockets. And they stay pretty cool the whole time. No pod filters. So what does that mean? And I checked plugs 1 & 3 for spark so if all plugs have spark but only 2 & 4 work on cylinders 2 & 4...

don't all the plugs fire the same or no? Apparently not since putting plugs 1 & 3 in 2 & 4 sockets didn't work. So does that mean 1 & 3 and 2 & 4 are staggered firing patterns? This one seems a bit weird no?

Do you have spark on 1&3? Do you have the right HT leads going to the correct plugs? On mine 1&4 are connected to the left hand coil 2&3 on the right coil. If you turn it over do the plugs 1&3 become wet? Where a outs are you?

Riche wrote:Do you have spark on 1&3? Do you have the right HT leads going to the correct plugs? On mine 1&4 are connected to the left hand coil 2&3 on the right coil. If you turn it over do the plugs 1&3 become wet? Where a outs are you?

Before I put my carbs back up (after cleaning/replacing rubber) I got all four to spray into the throats (on the rack) and before I ever touched my valves 1&3 weren't firing. I switched the plugs and wires for each coil pair individually and the spark plugs too, no difference, so plugs wires and coils good correct?

Something IS going on with 1&3 since when I take out the plug wires for either the engine doesn't run as good then died a couple times, more abruptly with #1 than 3.

Here's a short vid so you can hear the engine if it tells you anything.

Riche wrote:Does the engine run on 4 cyl when you rev it up?. If it only running on 2 cyl it should be very lumpy/ hard to rev? Do the pipes 1&3 only stay cold on idle?

Rich

not hard to rev at all, which tells me half of it is pretty strong lol. It's like they're barely working as they only get warm. Seems like something is off like in the valves but I spent a lot of time getting clearances right. But I did do it wrong then run the engine BUT they weren't firing before I first adjusted my tappets, so perhaps PO messed them up and they're bent or something causing too much fuel? IDK. So maybe timing and compression check? Timing is right for 2 & 4 so then should be right for 3 & 1 respectively right? So bad valves or bad pistons? 7k miles only but 35 yrs old. Do sitting young pistons get old? I rings I guess. Arent they metal? Compression SHOULD be good right? PO did a bad valve job I bet before I did my own bad job. But is it common to bend valves by doing your clearances wrong. have yet to read about that. IDK. You tell me.

It’s hard to say if the other cylinders are kicking in after 2k from your video just a loud ticking sound can be heard. Yes timing & compression test is probably a wise move. Remove the carbs first..Yes the timing is set for all 4 cylinders.

Hi jj, I had the exact same problem with my Custom, 1 and 4 weren't firing properly and both headers were cold, but 2 and 3 were fine. With me being crap with multimeters I opted for the "simpler" approach , I started swapping parts from my Nighthawk with parts from my Custom, I knew the Nighthawk was running on all four.I swapped both coils first, no change , then I swapped the spark igniters (under the seat), no change , then I swapped the ECU, no change That only left the pick ups on the right side of the crank , as I was about to change those next, I unplugged the connectors and noticed there was a lot of crap inside the block so I set to cleaning all of the electrical connectors on the ignition circuit with small strips of fine emery, electrical contact cleaner and compressed air, some connectors were slightly loose so I crimped them a bit with long nose pliers. I cleaned and checked the gaps on the pick ups with a sheet of paper and fired her up. She was running on all four, if a bit rough, but it was still on all four. Ticked over fine after she got warm but didn't like much throttle so I removed and cleaned the timing advancer mech behind the pick up plate, she ran nice and revved up ok I swapped the parts back on to the Nighthawk and fired her up again, still running nice, the problem was in my wiring and not in any components.

GeorgeSweety wrote:Hi jj, I had the exact same problem with my Custom, 1 and 4 weren't firing properly and both headers were cold, but 2 and 3 were fine. With me being crap with multimeters I opted for the "simpler" approach , I started swapping parts from my Nighthawk with parts from my Custom, I knew the Nighthawk was running on all four.I swapped both coils first, no change , then I swapped the spark igniters (under the seat), no change , then I swapped the ECU, no change That only left the pick ups on the right side of the crank , as I was about to change those next, I unplugged the connectors and noticed there was a lot of crap inside the block so I set to cleaning all of the electrical connectors on the ignition circuit with small strips of fine emery, electrical contact cleaner and compressed air, some connectors were slightly loose so I crimped them a bit with long nose pliers. I cleaned and checked the gaps on the pick ups with a sheet of paper and fired her up. She was running on all four, if a bit rough, but it was still on all four. Ticked over fine after she got warm but didn't like much throttle so I removed and cleaned the timing advancer mech behind the pick up plate, she ran nice and revved up ok I swapped the parts back on to the Nighthawk and fired her up again, still running nice, the problem was in my wiring and not in any components.

oooh, thanks for sharing. Didn't even know those parts you speak of exist. Can't wait to go digging in there... Wait, I swapped the plugs, cables on both coil and plug ends of each coil individually to confirm that the problem couldn't be with the electric parts. Wouldn't that be confirmation?

You would really have to work your way up from the pick ups on the right side of the crank, first check if you have a spark? is it a good spark? does it match the quality of the other cylinders that are firing ok?